This study focused on rainfall infiltration into pavement, water movement in the permeable base,and retrofit underdrain of pavement by means of numerical simulation. The pavement examinedwas a new asphalt pavement section with an underdrain retrofit after reconstruction and anasphalt overlay on the top of a cracked and seated (C & S) jointed reinforced concrete pavementwith underdrain retrofit after rehabilitation on Indiana SR-49. In order to provide highwayengineers with a methodology to analyze water migration and drainage into pavement systems, afinite-element model of the pavement was developed and a number of numerical analyses wereperformed to evaluate the movement of water in the pavement using the SEEP/W 2004 program.Unsaturated flow analysis was used to obtain the flow path of the infiltrated water and fluxquantity through a cross-sectional area in the pavement. The performance of the underdrainsystem was evaluated considering various levels of precipitation, cracks, permeable base andunderdrain, and subgrade soil-water characteristic curves (SWCCs). The findings of this researchrevealed that pavement sections without cracks on the surface can still accommodateapproximately 20% to 60% of the rainfall volume. How much water actually infiltrates into thepavement depends on the rainfall type, and an edgedrain can easily outflow most water within afew hours if the underdrain is in good condition. Therefore, the infiltration of water into thepavement structure should be addressed when designing pavement. When pavement isrehabilitated, a hot mix asphalt (HMA) overlay C & S jointed plain concrete pavement (JPCP)layer in conjunction with a retrofit underdrain can function as an efficient method for subsurfacedrainage. In addition, this study shows that newly constructed full-depth asphalt with a drainagelayer can also provide excellent drainage. Pavement underdrainage should be considered inplanning future reconstruction and rehabilitation projects.
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